1. Field of the Invention
The invention relates to the testing of firearms and is directed more particularly to measuring velocities of projectiles, such as bullets.
2. Description of the Prior Art
Until recently, it has not been feasible to shoot bullets underwater. Currently, however, supercavitation drag reduction allows bullets to be fired underwater at velocities sufficient to inflict damage on a target, explode mines, and the like.
It is known to measure velocities of bullets fired underwater. A fired bullet passes through a number of motion detector sensors in a sequential manner, the sensors being generally aligned with the expected trajectory of the bullet.
In U.S. Pat. No. 5,778,725, issued Jul. 14, 1998, in the names of Ivan N. Kirschmer et al, there is shown and described an assembly for testing an underwater gun. The assembly includes motion detector sensors, each comprised of a coil of copper windings in alignment with the expected trajectory, such that a tested bullet passes through the coils in its passage through the assembly. When the test bullet, which may be provided with a magnet, passes through a coil, such passage generates an electromotive force in the coil which is passed to a timer recording device. The timer recording device, in addition to recording the time of passage of the bullet, and having programmed therein the distance between sensors, determines the velocity of the bullet between each two sensors.
Referring to FIG. 1, It will be seen that a known motion sensor 20 comprises a thin support sheet 22 of plastic, or the like, retained in a rigid frame 24. An electrically conductive wire 26 is mounted on the sheet 22, as by printed circuit membrane methods, and is arranged such that a bullet passing through the sheet 22 will necessarily interrupt the wire 26 in one or more bullet hole areas 28. The sheet 22, frame 24, and wire 26 combination is generally referred to as a xe2x80x9cbreak-screenxe2x80x9d 30. The conductive wire 26 is in communication with a power supply and amplifier device 32 which, in turn, is in communication with a data collection/display apparatus 34 which provides an indication as to the times at which the break-screens are sequentially broken, and computes therefrom the time taken for the bullet to travel between break-screens 30, and, therefrom, the velocity of the projectile.
Referring to FIGS. 2 and 3, it will be seen that the above-described assembly may include a series of sequentially arranged break-screens 30 placed in a water container 36, such as a test tank or natural pond, or the like. The break-screens 30 are placed in an expected trajectory 38 of a bullet, or other projectile, fired from a gun 40. In a test tank, an array 42 of break-screens 30 may be mounted on carriage rails (not shown), or the like, normally provided in test tank assemblies. In a pond, or the like, the array 42 of break-screens 30 may be suspended from a floating barge 44, or other vessel.
A shown in FIG.3, each break-screen 30 is provided with an amplifier 32, each of the amplifiers 32 being adapted for connection to the collection/display apparatus 34.
Inasmuch as the array 42 may include from two to forty-eight, or more, break-screens, it is deemed beneficial to remove the amplifiers 32 from the break-screens 30, such that the requirement of large numbers of amplifiers for a given assembly is eliminated and the handling of break-screens, comprising only the sheet 22, wire 26 and frame 24, is simplified.
An object of the invention is, therefore, to provide an apparatus for measuring the velocity of a projectile, the apparatus including a selected number of break-screens and a single common amplifier for all of the break-screens.
With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of an apparatus for measuring velocity of the projectile, the apparatus comprising a plurality of break-screens aligned with each other serially and along a line of travel of the projectile, and parallel to each other, and spaced from each other and from a projectile firing device by selected distances. Each of the break-screens comprises a support sheet and an electrically conductive wire mounted on the sheet so as to be interrupted by passage of the projectile through the sheet. An amplifier is in communication with each of the conductive wires and is adapted to provide an indication as to a change in voltage in each of the break-screens upon passage of the projectile therethrough, and an indication as to time of the passage. A data collection/display apparatus provides an indication as to the times at which the break-screens are broken, from which there is computed the velocity of the projectile.
The above and other features of the invention, including various novel details of construction and combinations of parts, will now be particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular apparatus embodying the invention is shown by way of illustration only and not as a limitation of invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.